FDX-B 134.2 kHz RFID reader

Other Hardware General Electronics
78

im having trouble with @red_car code. my module came with a worked example and I tired having it run through that example with the code but its not correctly producing the TAG ID

the example is:

02 31 37 31 41 39 32 35 33 41 33 34 38 33 30 30 31 30 30 30 30 30 30 30 30 30 30 07 f8 03

which when converted through ASICII: 171A9253A34830010000000000

which contains:

tag id: 1-10 byte (10 long)

country code bytes 11-14 (4 long)

171A9253A3 483 0010000000000

which should produce: country: 900 tag: 250000023921

byte buffer[30] = {0x02, 0x31, 0x37, 0x31, 0x41, 0x39, 0x32, 0x35, 0x33, 0x41, 0x33, 0x34, 0x38, 0x33, 0x30, 0x30, 0x31, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x07, 0xf8, 0x03};
byte b;
uint8_t idx;
boolean started = false;

byte     XOR;
byte     inverted;

uint32_t   value;


void setup() {
  // Initialize serial communication at 9600 baud
  Serial.begin(9600);
  delay(1000);
  Serial.println("start:");
}

void loop() {
  
        // Print the contents of the buffer to Serial Monitor for verification
        for (int i = 0; i < sizeof(buffer); i++) {
          Serial.print(buffer[i], HEX);
          Serial.print(" ");
        }
        Serial.println();

        // Check we received the message ok.  XOR checksum on bytes 01-26 should match byte 27.
        XOR = buffer[1];
        for (int x = 2; x <= 26; x++)
        {
          XOR ^= buffer[x];  
        }
        Serial.print("Calculated checksum: ");
        Serial.print(XOR, HEX);

        if (XOR == buffer[27])
          Serial.println(" (Correct)");
        else
          Serial.println(" (Error)");


        // Check the inverted XOR checksum
        inverted = ~XOR;
        Serial.print("Inverted checksum: ");
        Serial.print(inverted, HEX);
        if (inverted == buffer[28])
          Serial.println(" (Correct)");
        else
          Serial.println(" (Error)");

        
        // Extract the card number from bytes 01 (LSB) - 10 (MSB).
        value = 0;
        for (int x = 10; x >= 1; x--)
        {
          if(buffer[x] <= '9')
            value = (value<<4) + buffer[x] - '0';  
          else
            value = (value<<4) + buffer[x] - '7';  
        }
        Serial.print("Card number: ");
        Serial.println(value);


        // Extract the country number from bytes 11 (LSB) - 14 (MSB).
        value = 0;
        for (int x = 14; x >= 11; x--)
        {
          if(buffer[x] <= '9')
            value = (value<<4) + buffer[x] - '0';
          else
            value = (value<<4) + buffer[x] - '7';  
        }
        Serial.print("Country number: ");
        Serial.println(value);


        // Extract the Data Block from byte 15.
        Serial.print("Data block: ");
        Serial.println(buffer[15] - '0');

        
        // Extract the Animal Flag from byte 16.
        Serial.print("Animal flag: ");
        Serial.println(buffer[16] - '0');

        Serial.println("\r");
delay(100000);
}

which returns the card id: 891920753

2 31 37 31 41 39 32 35 33 41 33 34 38 33 30 30 31 30 30 30 30 30 30 30 30 30 30 7 F8 3 
Calculated checksum: 7 (Correct)
Inverted checksum: F8 (Correct)
Card number: 891920753
Country number: 900
Data block: 0
Animal flag: 1